RESUMO
Retroperitoneal leiomyosarcoma is relatively uncommon. Leiomyosarcoma has accounted for about 5%-10% of soft-tissue sarcoma, and 1/2–2/3 of the primary lesions were retroperitoneal, with a cumulative 5-year survival rate of only 35%.Leiomyosarcoma is one kind of soft-tissue sarcoma with the lowest survival rates due to the invasive growth, difficult treatment, and poor prognosis.The present study reported a case of a 78-year-old male diagnosed as left retroperitoneal leiomyosarcoma, who had received three operations. Computed tomography (CT) demonstrated a mass of approximately 12.9 cm × 6.9 cm × 6.6 cm in his retroperitoneal region. The Eastern cooperative oncology group and numerical rating scale scores of pain were 1 and 5, respectively. Multiple treatment strategies were administered, including the application of drainage and125I seed implantation. A total of 90125I seeds were implanted into the tumor through repetitious operations, with 30 seeds each time. Treatment planning system was involved to calculate the source distribution.125I seeds with the activity of 0.5 mCi were implanted under the guidance of CT, and dosimetric verification was performed after the operation. D90 (90% minimum prescription dose received by target volume) was 40 Gy. Follow-up was performed after 6 months, and complete response was achieved in the local lesions. However, there was no evidence-based treatment currently and the majority of our knowledge was based on results from case reports, thus further studies would be required